I suppose you could create a toggle for this option and map that onto a hotkey, put it into a sculpting pie menu or execute it as a script that runs when you activate sculpt mode as well as untoggle it again on exit? If you activate 'Developer Extras' 'Python tooltips' from the 'Interface' page of the preferences you can…
They're heavier than bones to be sure but if all you're doing is rendering out an animation with a few characters the time it saves you is well worth the cost. Epic used a blend shape rig with their kite demo and it was basically fine. If you want to make sure that it's super optimized you could potentially split the head…